屢試不爽 [屡试－－]

Jyutping leoi5 si3 bat1 song2
Pinyin lǚ shì bù shuǎng

Definitions (CC-CEDICT)
  1. well-tried
  2. time-tested
Definitions (Wiktionary)
  1. phrase, idiomatic
    to prove effective every time
Definitions (Kaifangcidian)
  1. （沒有對應漢語詞彙）